Some conveyance devices for precise fine workpieces such as semiconductor chips are of a type which mounts the fine workpieces on an upper surface of a rotating table serving as a rotating body to convey them up to a target position and concurrently exerts their processes or inspections in each mounting state. Thereamong, a vacuum feeding joint, in which an air adsorption section is provided on the upper surface of the rotating table and a vacuum feeding source is connected to the fixed base supporting the rotating table, is known as the above-described conveyance device capable of mounting the fine workpieces on the upper surface of the rotating table with high precision. In the vacuum feeding joint, a communication passage for communicating with the air adsorption section and the vacuum feeding source is formed in each of the rotating table and the fixed base, whereby the fine workpieces mounted on the air adsorption section can be adsorbed and fixed with high precision.
In the above-mentioned vacuum feeding joint, to be capable of supplying a vacuum even if the rotating table is rotated at any angle, an annular communication groove, in which a rotating shaft of the rotating table serves as a center, is formed in at least one of a bottom surface of the rotating table and the upper surface of the fixed base and, concurrently, a communication passage communicating with the air adsorption section and a communication passage communicating with the vacuum feeding source are opened on a circumference of the annular communication groove, respectively. Additionally, seal members contacting with the rotating table and the fixed base are mounted on an outer-circumference side and an inner-circumference side of the annular communication groove, whereby the seal members ensure airtightness of the communication passages.
However, if the seal members are thus mounted, friction is caused in rotate-driving the rotating table, so that it is difficult to smoothly rotate the rotating table at a precise rotating angle.
An object of the present invention is to provide a vacuum feeding joint capable of ensuring the airtightness in the communication passages during the feeding of a vacuum supplying and suppressing an occurrence of friction during the rotate-driving of the rotating body.